The invention relates to a device for mixing two paste-like compounds for a dental-molding compound and a catalyst for the acceleration of polymerization. The device has a housing, which has a mixing area with at least two inlet openings for the two paste-like compounds and an outlet opening for the mixed paste-like compound. The device also has a mixing element that is arranged so that it can be especially propelled in the mixing area and is pivotable in the housing along its longitudinal axis. The housing also has a coupling section that is situated in front of the mixing area with two coupling openings for connecting with two dispensing openings of a device for dispensing the two paste-like compounds. A first and a second duct connect to the coupling openings, extending through the coupling section to the inlet opening for the mixing area. The two ducts are formed so that the time needed for the entry of the paste-like compound into the coupling opening of the coupling section, until the entry into the inlet opening of the mixing area of the housing, is greater for the first duct than for the second duct.
The device is attached to the two outlet supports of a delivery device, wherein the compounds to be mixed are inserted into the mixing device by applying pressure to the compounds. After these compounds are mixed in the mixing device, they are dispensed from this device as one compound.
In numerous technical application areas it is necessary to apply two separately stored paste-like compounds in a mixed form. Here either a dynamic or a static flow mixer is used such as a mixer with a moveable or stationary mixing element, which mixes the compounds with each other while flowing through the mixing housing.
A dynamic mixer is known from U.S. Pat. No. 5,249,862. This known device has a mixer housing that is essentially tube-shaped with a pivotable mixer element arranged in it. The mixer element has a number of radially protruding rib-like mixer arms that rotate around the flow of compounds, and thus mixes the two paste-like compounds with each other when the mixer element is driven. The paste-like compounds reach the mixer element via a radial front wall at the back end of the mixer housing. Thus, the front wall has two inlet supports, which are attached to the outlet supports of the device for yielding the paste-like compounds.
However, regardless of whether a static or dynamic mixer is used, the above devices encounter problems because of the uneven flow of the different mixing components and thus the uneven amounts of the components in the mixing region.
It is already known that the problem can be constructively dealt with by having the base component or components within the mixer that tend to overdose flow a longer way to the mixer element than the other component or catalyzing components. This flow is between the reserve receptacle and the mixer. A first example for such a concept is described in DE-U-298 18 499, according to which the duct of the one component runs in the form of an arch around the longitudinal axis of the pivotable mixer element between the inlet of a dynamic mixer to the actual mixer area. An example for solving the problem in the case of a static mixer is given in U.S. Pat. No. 6,135,631, whereby this mixer was already on the market before the application date of the subject of DE-U-298 18 499, and was freely distributed and disbursed to third parties. Also for these known static mixers, the base component that tended to overdose was redirected in an arch-like form in the mixer, and the flow of compounds was divided in two, to reach the stationary mixing element next to the compound flow of the other component or other catalyzing component. In so doing, the introduction of the non-advancing (catalyzing) component flows as directly as possible, i.e. without any detours that would increase the flow resistance. Further examples for such mixers which delay the advancement of faster flowing compounds serving as dead volume are known from U.S. Pat. No. 5,487,606, and EP-A 0664 153.
In the case of the known mixers, a recontamination can occur after the deploying process ends, such as when the application device is shut off. This can occur because the base component flows into the container of the catalyzing component due to the varying pressure in the reserve receptacles of the paste-like compounds. If these components mix with each other and polymerize or harden in the deploying duct of one of the reserve receptacles of the paste-like compounds, the entire reserve receptacle and its content are unusable.
The present invention provides an additional device for mixing two paste-like compounds, whose mixing ratio is constant from the beginning of the dispensing of the mixed compounds, and also prevents a recontamination of these two compounds.